JPH04265617A - Connection structure of cable - Google Patents

Abstract

PURPOSE:To provide a part to which a voltage for cable withstand voltage test is applied at a cable connecting part that is installed on a case for housing an electric appliance which one end of a cable is connected to. CONSTITUTION:A test bushing 26 is removably attached to a cable connecting part 3 to which a cable sheath 14 is connected. Then, a conductor 11 which is connected to the cable sheath 14 through a solderless contact 12 and a conductor 27 which is buried in the epoxy resin 28 are connected to each other through a contact 25. The test bushing 26 is connected to the cable connecting part 3 only at the time of the cable withstand voltage test. At other times, the bushing 26 is disconnected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable connection structure that allows easy application of voltage for testing cable withstand voltage.

0002

2. Description of the Related Art FIG. 5 shows a sectional view of a main part of a closed type switchgear whose housing is filled with an insulating gas such as SF6 gas. As shown in the figure, a cable (power supply side or load side) 1 is connected to a circuit breaker (not shown) via a cable connection part 3 attached to a housing 2, a connection conductor 4, a switchable disconnector 5, and a connection conductor 6. Connected. A grounding device 7 is provided on the connecting conductor 4, and includes a connecting conductor 8, a grounding bushing 9, and a grounding conductor 10.
grounded via.

Next, the structure of the cable connection section 3 will be explained based on FIG. 6. In the figure, 11 is a conductor, 12 is a compression terminal,
13 is a cable conductor, 14 is a cable sheath, 15 is a device side receiver, 16 is an insulating cylinder, 17 is a spacer, 18 is an insulator, and 19 is a waterproof tape.

A protruding threaded portion 11a is formed on the conductor 11, and after the threaded portion 11a is inserted into the hole 12a of the compression terminal 12, a nut 20 is tightened onto the threaded portion 11a. An insulating plug 21 made of epoxy resin is fitted into the upper right corner of the spacer 17, and a screw portion 11a and the like fit into the recess 21a of the insulating plug 21. A protective cover 22 is placed over the outside of the insulating plug 21.

[0005] Article 13 of the Electrical Equipment Technical Standards stipulates the dielectric strength test of cables used in high voltage and extra high voltage electrical circuits, and conventionally the grounding bushing 9 was used as a voltage application terminal for carrying out the dielectric strength test. It is used as. To perform this test, as shown in Figure 5, after installing the switchgear on site and connecting the cables, disconnect the disconnector 5, connect the grounding device 7, and remove the grounding conductor 10 to ground it. A voltage is applied to the bushing 9 from outside the housing 2.

[0006]

[Problem to be solved by the invention] However, the grounding device 7
The grounding bushing 9 is used to measure the insulation resistance of cables, and its withstand voltage value of about 1000 V is originally sufficient.
Since these are also used for cable withstand voltage tests, the withstand voltage value must be made higher. This results in
The insulation distance of the grounding device has become larger, the insulator for supporting the earthing device and the grounding bushing have become larger, and the insulation distance of the grounding bushing in the air has also become larger, which is a factor that prevents the downsizing of switchgear. . In addition, bushings designed to withstand voltages for cable tests are several times more expensive than bushings for measuring insulation resistance, and because they are only used for cable installation and are used extremely infrequently, bushings that can withstand voltages used for cable tests are often used in constant switching devices. It is a waste to keep it. Further, when the other end of the cable is exposed to the air, the test voltage can be applied from the other end, so there is no need to take the trouble to provide a voltage application section on the switchgear side.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cable connection structure that solves the above problems.

[0008]

[Means for Solving the Problems] The structure of the present invention for achieving the above object is to house an electrical device inside a housing, fill it with insulating gas, and cover a cable connection portion covered with an insulating member within the housing. In a cable connection structure in which the cable connection part is attached to the electrical equipment and one end of the cable is connected to the part of the cable connection part located outside the case, a test bushing for applying cable withstand voltage used only during testing is used. It is characterized by being detachably provided on the outside of the casing at the cable connection part.

[0009]

[Operation] After installing the switchgear etc. on site and laying the cable, a test bushing is attached to the cable connection part, and a voltage for cable withstanding voltage test is applied to the outer end of the test bushing. When the cable withstand voltage test is completed, remove the test bushing from the cable connection and normally operate the switchgear without the test bushing.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on embodiments shown in the drawings. It should be noted that this embodiment is an improvement on a part of the conventional cable connection structure, so the same parts as the conventional cable are given the same reference numerals and explanations are omitted, and only the different parts will be explained.

The configuration of a first embodiment of the cable connection structure according to the present invention is shown in FIGS. 1 to 4. In the present invention, the insulating plug 21 and the protective cover 22 are removed and the test bushing 26 can be detachably attached as shown in FIG. The grounding bushing 9 used is smaller than the conventional one. As shown in FIG. 1, the test bushing 26 has a conductor 27 embedded inside an epoxy resin 28 having a substantially cylindrical shape. Conductor 27 and conductor 11
The connection part with is shown in Figure 2. A projection 27a is formed at the end of the conductor 27, and a threaded portion 11a in FIG.
A plurality of contacts 25 are installed between the protrusion 11b and the protrusion 27a provided at the tips of
are provided, and a garter spring 29 is wound around the contacts 25 so as to bundle them together. Then, a holder 30 is attached to the protrusion 27a to prevent the contactor 25 from coming off the protrusion 27a. If the test bushing 26 is heavy or the pressing force against the cable attachment part 3 is insufficient, a mounting bolt 31 may be used as shown in FIG. 1.

Next, the structure of the second embodiment is shown in FIG. This forms a tapped hole 32 at the end of the conductor 27, while
The threaded portion 11a shown in FIG. 6 is made longer than the conventional one, and the threaded portion 11a is screwed into the tapped hole 32. The other parts are the same as in the first embodiment.

Next, the operation of such a cable connection structure will be explained. When performing a cable withstand voltage test, please refer to Figure 4.
After the disconnector 5 is disconnected and the grounding device 7 is connected, the protective cover 22 and insulating plug 21 shown in FIG.
Remove the test bushing 2 from the cable connection part 3.
6 is attached, and the conductor 11 and the conductor 27 are connected. Thereafter, a test voltage is applied from the outer end of the conductor 27 located in the atmosphere with the grounding device 7 in an ungrounded state. After the test is completed, the test bushing 26 is removed in the reverse order as described above, and the insulating plug 21 and protective cover 22 are attached.

[0014]

[Effects of the Invention] As can be seen from the above explanation, according to the cable connection structure according to the present invention, the test bushing is detachably attached to the outside of the casing at the cable connection part, so that There is no need to apply voltage for cable withstand voltage tests to the grounding bushing. Therefore, the grounding device and the grounding bushing only need to withstand about 1000V, which is the voltage for insulation resistance, and therefore, their dimensions can be reduced, and the downsizing of the switchgear is not hindered and the cost is reduced.

[0015] Furthermore, since the test bushings are used only a few times, they can be stored at the manufacturer. Furthermore, since the test bushing can be removed and stored, there is less risk of bushing deterioration compared to when it is permanently installed in a switchgear, etc., and it is necessary to take into account the deterioration of the bushing when applying voltage again due to cable installation etc. There is no.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cable connection section showing a first embodiment of the present invention.

[Fig. 2] Fig. 2(a) is a BB arrow view of Fig. 2(b), Fig. 2
(b) is an enlarged view of section A in FIG.

FIG. 3 is a sectional view of a cable connection section showing a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a switchgear according to the present invention.

FIG. 5 is a sectional view of a main part of a conventional switchgear.

FIG. 6 is a sectional view of a conventional cable connection section.

[Explanation of symbols]

1...Cable 2...Housing 3...Cable connection part 26...Test bushing

Claims (1)

[Claims] Claim 1: A case in which an electric device is housed and filled with insulating gas, a cable connection portion covered with an insulating member is attached to the case, and the cable connection portion is connected to the electric device; In a cable connection structure in which one end of the cable is connected to an external part, a test bushing for applying cable withstand voltage used only during testing is detachably provided outside the casing at the cable connection part. cable connection structure.